Occurrence of secondary fracture around intramedullary nails used for trochanteric hip fractures: A systematic review of 13,568 patients

Abstract

Introduction

A sliding hip screw (SHS) is currently the treatment of choice for trochanteric hip fractures, largely due to the low incidence of complications. An alternative treatment is the use of intramedullary proximal femoral nails. Unfortunately these implants have been associated with a risk of later fracture around the implant. The aim of this study was to see if any improvements have been made to the current intramedullary nails, to reduce the incidence of secondary fracture around the distal tip of the nail.

Methods

We analysed data related to 13,568 patients from 89 studies, focusing on the incidence of post operative secondary femoral shaft fracture following the use of intramedullary nails in the fixation of trochanteric hip fractures.

Results

The overall reported incidence of secondary fracture around the nail was 1.7%. The incidence of fracture has reduced in the 3rd generation Gamma nails when compared to the older Gamma nail (1.7% versus 2.6%, p value 0.03). However, the incidence of secondary fracture in the 3rd generation Gamma nails is still significantly higher than the other brands of short nail (1.7% versus 0.7%, p value 0.0005). Long nails had a slight tendency towards a lower risk of fracture although the difference was not statistically significant (1.1% versus 1.7%, p value 0.28). There was a significantly lower risk of fracture for those nails with a biaxial fixation as opposed to uniaxial fixation (0.6% versus 1.9%, p value <0.0001).

Conclusion

Secondary fracture around a proximal femoral nail is one of the most significant of fracture healing complications, and this study suggests that continuing design changes to this method of fixation has reduced the risk of this complication occurring.

Introduction

A proximal femoral fracture or hip fracture is the most common reason for admission to an acute orthopaedic ward.¹ Trochanteric hip fractures (AO classification 31-A) account for approximately half of all these hip fractures. The current evidence recommends the use of a sliding hip screw and plate (SHS) because of the low incidence of complications and failure, and high rates of fracture union.² Because of perceived biomechanical advantages of intramedullary fixation, with a shorter leaver arm, intramedullary nails have been used with increased frequency for the fixation of trochanteric hip fractures.3, 4

Concerns have been raised that the incidence of fracture healing complications is increased for the intramedullary nails used in the fixation of trochanteric hip fractures in comparison to the more traditional SHS fixation.² No difference in the incidence of cut-out of the femoral neck screw has been shown between the intramedullary nails and SHS's, and intramedullary nails avoid the complication of detachment of the plate from the femur. Other complications occurring in both groups include non-union, avascular necrosis of the femoral head, implant breakage and disassembly of the implant. However, intramedullary nails incur the risk of secondary fracture around the distal tip of the implant, which is rare after a SHS fixation with a reported incidence in a summary of randomised trials of 2/1645 (0.1%).²

The first widely available intramedullary device used in the fixation of hip fractures was the Gamma nail (Howmedica/Stryker) which was introduced in the 1980s. Design modifications have been made to this nail since then such that currently versions include the Gamma 3 nail, Trochanteric Gamma nail and the Gamma AP (Asia Pacific) nail. A recent study of the Gamma nail has suggested that the risk of secondary femoral shaft fractures is no longer increased.⁵ A number of other designs of proximal femoral nails have been introduced from different manufacturers. These include the intramedullary hip screw (Smith and Nephew), Proximal femoral nail (Synthes), Proximal femoral nail anti-rotation (Synthes), Trochanteric fixation nail (Synthes), Holland nail (Biomet), Targon PF nail (Aesculap) and the Ace trochanteric nail (DePuy/Johnson & Johnson).

Because of the severity of this complication, which leads to either a prolonged period of traction, or revision surgery, and its possible reduction with the modification of the nail designs, we have undertaken a systematic review and meta-analysis of all published data relating to the incidence of post-operative secondary femoral shaft fractures in all types of intramedullary nails used in the management of trochanteric (AO classification 31-A) hip fractures over the last 30 years.

We identified the study population using a Medline search of the English literature from 1980 to 2010. We used the key words “extra capsular fracture” or “trochanteric fracture nail”. We also used the “related articles” feature in PubMed (www.ncbi.nlm.nih.gov/pubmed) to identify similar studies. We included all case series and randomised controlled trials, but excluded all reviews. We included data from all studies on intramedullary nailing of trochanteric hip fractures, but excluded data on operative fractures or early post-operative fractures that were attributed to a missed operative fracture of the femur, and studies of purely subtrochanteric fractures. We excluded all peri-operative fractures because we were trying to study a post-operative complication. We excluded all non-English language studies.

Two observers independently extracted the data for the population, intervention, incidence of secondary femoral shaft fracture and time from operation to secondary femoral shaft fracture from each relevant article. Differences were resolved by discussion between all three authors, and a joint review of any papers where there was a difference of opinion.

We pooled data across studies and calculated p values for each comparison using the Chi-square statistic with Yates correction for unequal variances. Statistical analysis between the groups was carried out using GraphPad InStat version 3.00 for Windows 95, GraphPad Software, San Diego, CA, USA.